The p53 tumor suppressor protein belongs to a superfamily of transcription factors. p53 is involved in a wide range of cellular activities that help ensure the stability of the genome and is involved in DNA damage repair, cell cycle arrest, and apoptosis via transcriptional regulation of genes involved in these activities or by direct interaction with other proteins. Mutations that inactivate p53 are present in over 50% of all cancers and are indicative of aggressive cancers that are difficult to treat by chemotherapy or ionizing radiation. The majority of inactivating mutations reside in the central core DNA binding domain (DBD)1 of p53. These mutations can be divided into two main classes, DNA contact mutants, like R273H, where the mutation alters a residue involved in contact with DNA, and structural mutants, like R249S, which result in structural changes in the p53 core domain.
One potential therapeutic approach to cancer would be restoration of growth suppression activity to mutant p53. Several approaches have been tried, ranging from microinjection of monoclonal antibody 421, C-terminal peptide of p53 and small molecules (Abarzua et al., Oncogene 13: 2477-2482 (1996); Abarzua et al., Cancer Res. 55:3490-3494 (1995); Halazonetis et al., EMBO J. 12:1021-1028 (1993); Wieczorek et al., Nat. Med. 2: 1143-1146 (1996); Selinova et al., Mol. Cell Biol. 19, 3395-3402 (1999); Peng et al., Oncogene 22: 4478-4487 (2003)). Recently, small molecules and peptides, such as CP-31398, PRIMA1, and CDB3 peptide, have been shown to be effective in restoring p53 function (Foster et al., (1999) Science 286: 2507-2510; Bykov et al., Nat. Med. 8, 282-288 (2002); Friedler et al., Proc. Nat. Acad. Sci. U.S.A. 99, 937-942 (2002); Freidler et al., J. Biol. Chem. 278, 24108-24112 (2003); Issaeva et al., Proc. Nat. Acad. Sci. U.S.A. 100, 13303-13307 (2003); Luu et al., Exp. Cell Res. 276: 214-222 (2002); Wang et al., Mol. Cell Biol. 23, 2171-2181 (2003); Wischhusen et al., Oncogene 22, 8233-8245 (2003); Takimoto et al., Cancer Biol. Ther. 1, 47-55 (2002)).
There exists a need in the art for assay methods by which agonists of p53 function may be quickly and conveniently identified.